Vortex shedding analysis of flows past forced-oscillation cylinder with dynamic mode decomposition

Direct numerical simulations are performed for flow past circular cylinders by the lattice Boltzmann method coupled with immersed moving boundary method. By analyzing flows a single cylinder at wide range of cross-flow or in-line oscillation amplitude (0.25≤A/D≤1.5) and frequency (0.5≤fe/f0≤1.5), results find that vortex shedding modes inside outside “lock-in” interval significant difference. The mode in “unlock-in” state is 2S, but C(2S) P + S can be found lock-in state. Dynamic decomposition used to analyze characteristic features, which shows 1 main factor reflecting field structure 2 represents this work. tandem side-by-side double oscillating systemically investigated. For cylinders, modal suggest shear layer upstream separated behind downstream space rate L/D≤2, L/D≥3. Mode L/D=4 differs from other due strong inhibition effect on formation cylinder. wake two street H/D=1, bistable H/D=2 3, H/D=4, close H/D>4. disordered interaction between gap flow.